AQA GCSE Changes of State
Changes of State
A change of state is a physical change, this means that the change is reversible, when the process is reversed the material regains its original properties.
If ice is melted to form liquid water and then frozen to reform ice, the ice that is formed has the same properties as the ice at the start.
Change of state triangle
Learn the names of the different processes
In the
Key terms:
Melting is when a solid forms a liquid
Freezing is when a liquid forms a solid
Boiling or evaporation is when a liquid forms a gas or vapour.
Condensing is when a gas forms a liquid.
Sublimation is when solid turns directly into a gas, missing out the liquid state. Iodine and solid carbon dioxide can both undergo sublimation.
Dry ice (solid carbon dioxide) on a spoon undergoing sublimation:
Solid dark grey iodine undergoing sublimation to form purple vapours:
Changes of state and mass
When a substance changes state, the number of particles will not change, so the mass of the substance will not change.
If 100g of ice is melted, then 100g of liquid water is formed. When this water is boiled, 100g of steam is formed.
Practice Questions
1.Explain what is meant by a change of state being a physical change.
2. In the winter liquid water forms on the surface of windows. State the name of the process that is responsible for the liquid water forming
3. 1500g of liquid propane is allowed to evaporate. State the mass in kg for the total propane vapours formed.
Absorption and Emission of EM Radiation
JJ Thomson and Plum pudding model
Ernest Rutherford and the Nuclear Model
Niels Bohr changing the Nuclear Model
Discovering the Proton and Neutron
Measuring radiation from radioactivity
Radiation types and properties
Random nature of radioactive decay
Radioactive contamination or irradiation
Hazards of contamination and irradiation
Studies on the effects of radiation on humans
Different half lives of radioactive isotopes
Nuclear Fission Chain Reaction
Writing nuclear fission equations